So to fix the said problem, you can follow the guide in this post. Firstly, download the latest iTunes 10.6.1 or newer version, and use Wifi or data as your internet connection.
How to fix Facetime and iMessage doesn't activate (Waiting for Activation) on iPhone.
Step 2. Open Cydia and then add the following url repo source. Do so by navigate to Manage >> Sources >>> Edit >> Add.
Step 3. After you added the url, now search and then install Cydia for SAM.
Step 4. After SAM is succesffully installed, now open SAMPrefs on your iPhone's Homescreen and then head to Utilities.
Step 5. Click on the Revert Lockdown to stock. You will get a message saying it's successful. And then click on De-Activate iPhone (clear push). You will get a success message appears for second times. Simply click on OK then to close it.
Step 6. Plug your iPhone to computer, and then launch iTunes. Don't worry if the error message appears, it means everything is fine. And then sync your device, do so by right-click on your device on the left window pane and then choose Sync.
Step 7. After the sync process completed, launch SAMPrefs on your iPhone and then click on More Information. If you get WildcardActivated, means you are on the right road, and you can continue to the next steps.
Step 8. Back to SAMprefs and go to Utilities. Click on Backup Activation on Restore Activation option. Then you'll find your iPhone respiring afterward.
Step 9. Reboot the device of yours, and then sync it with iTunes again. Once the sync completed. Open the Appstore and then search for iPusher and install it.
Step 10. After iPushes is installed successfully. Again, reboot your device. For the last time, sync your device to iTunes again. Afterward open iPusher. Then click on Test Push Notifications field, and after sometime, you will be notified with this message: Yay, push notifications work fine!
Step 11. Done. Now turn your FaceTime and iMessage ON. Do so by navigate to Settings > iMessage or Facetime to ON. Now they are fully activated. If otherwise, I mean you fail to activate them, then reboot your device once again and then try to turn them ON once more. This will work.
Congratulation now you have fixed FaceTime and iMessage Waiting for Activation problem on iPhone 3G or iPhone 4.